Motor Power, Torque & Battery Run Time for Miter Saw Tool

[Curious007]

I saw 15 Amp motor which runs on 120 VDC with 5500 rpm [This motor was attached to Miter Saw tool]. I'm not sure what's HP of that motor, but I read 5.5 HP, however the size of motor is around 6 inch long and 4 inch diameter (Is it possible this small motor have 5.5 Hp? And can we calculate torque of the motor based on above known facts?).

Now my other question is : Can I run this 120 VDC motor using this 20 Volt DC with 3 Ah rating battery? If so how long I can run this motor using it?

Thank you.

 

[russ_watters]

Well, 15A at 120V and 95% efficiency would be 2.3 horsepower.

I seem to remember that vacuum cleaner manufacturers play games with horsepower ratings, so it wouldn't surprise me if circular saw manufacturers did too.

 

[Curious007]

May be that was mistake of Shop guy who put 5.5 HP sticker on it.

But other thing is can we run that motor using 20 V DC battery with 3 Ah rating? for 1 or 1 minutes?

 

[sophiecentaur]

A 120V motor will not work on 20V. I doubt whether, on only 17% of its rated voltage, it will even rotate at all. Basically, with 17% Volts, you could expect to get just 2.8% of its power (i.e. 17% of 17%) - even if everything else was perfectly pro-rata - and there is a threshold below which nothing will happen. You might expect about 2.5A to pass.

BTW, the current that the motor will pass is determined basically by the supply volts - too few supply volts will just not make enough current flow. A low voltage motor is designed with much fewer coils of fatter wire (as in a car starter motor).

 

[alphysicist]

I can provide a response to your questions about the motor power, torque, and battery run time for the miter saw tool.

Firstly, the motor power of a 15 Amp motor running on 120 VDC and with a speed of 5500 rpm is approximately 5.5 HP. This is a common measure of power for motors, and it is possible for a motor of this size to have 5.5 HP. However, it is also important to consider the efficiency of the motor, which can affect the actual power output.

To calculate the torque of the motor, we would need additional information such as the weight of the saw blade and the distance from the center of the motor to the blade. With this information, we could use the equation T = F x d to calculate the torque, where T is torque, F is force, and d is distance.

As for your second question, it is possible to run the 120 VDC motor using a 20 Volt DC battery with a 3 Ah rating. However, the run time will depend on the efficiency of the motor and the load it is under. The higher the load, the shorter the run time will be. It is difficult to estimate exactly how long the motor can run on this battery without knowing the specific details of the motor and the saw.

In conclusion, the 15 Amp motor on the miter saw tool has a power of approximately 5.5 HP, and the torque can be calculated with additional information. It is possible to run the motor with a 20 Volt DC battery, but the run time will vary depending on the load. I hope this answers your questions.